Energy Consumption and Quality of Service (QoS) are two primary concerns in the development of today’s pervasive computing systems. While most of the research in energy-aware real-time scheduling has been focused on hard real-time systems, we study the problem of minimizing energy for soft real-time systems with the requirements of QoS-guarantee. In this paper, the QoS requirements are deterministically quantified with the (m; k)-constraints,which require that at least m out of any k consecutive jobs of a task meet their deadlines. A dynamic DVS algorithm is presented to reduce the energy while guaranteeing the given(m; k)-constraints. The simulation results demonstrate that our proposed techniques can achieve significant energy saving performance while ensuring the QoS guarantee.